Wurtzite Effects on Spin Splitting of GaN/AlN Quantum Wells

A new mechanism (DeltaC1-DeltaC3 coupling) is accounted for the spin splitting of wurtzite GaN, which is originated from the intrinsic wurtzite effects (band folding and structure inversion asymmetry). The band-folding effect generates two conduction bands (DeltaC1 and DeltaC3), in which p-wave probability has tremendous change when kz approaches anti-crossing zone. The spin-splitting energy induced by the DeltaC1-DeltaC3 coupling and wurtzite structure inversion asymmetry is much larger than that evaluated by traditional Rashba or Dresselhaus effects. When we apply the coupling to GaN/AlN quantum wells, we find that the spin-splitting energy is sensitively controllable by an electric field. Based on the mechanism, we proposed a p-wave-enhanced spin-polarized field effect transistor, made of InxGa1-xN/InyAl1-yN, for spintronics application.Comment: 12 pages, 4 figures (total 16 pages

Anomalous k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures

We have confirmed the k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures. Anomalous beating pattern in Shubnikov-de Haas measurements arises from the interference of Rashba and Dresselhaus spin-orbit interactions. The dominant mechanism for the k-dependent spin splitting at high values of k is attributed to Dresselhaus term which is enhanced by the Delta C1-Delta C3 coupling of wurtzite band folding effect

To sit or stand? A preliminary, cross sectional study to investigate if there is a difference in glenohumeral subluxation in sitting or standing in people following stroke

Background: Glenohumeral subluxation (GHS) is a common symptom following stroke. Many therapists postulate that GHS may be reduced if the base of support (BOS) is reduced and the centre of mass (COM) is raised as this requires greater postural muscle activity. However, there is little empirical evidence to support this practice. Objective: The aim of this preliminary study was to investigate if the amount of GHS alters from sitting to standing. Study design: A cross sectional, within-subject design in a convenience sample of 15 stroke patients with GHS was utilised. Methods: A prospective design was used with a single blinded tester who assessed GHS using the calliper method in sitting, standing and on return to sitting. Friedman and post hoc Wilcoxon tests showed that GHS was significantly reduced in standing compared to sitting (p <0.05) but this reduction was not maintained on return to sitting (p = 0.25). Conclusions: The results of this study are limited by its small size. However, these results indicate that reducing BOS during rehabilitation may improve GHS after stroke. Whilst the maintenance of benefit is not established, these findings suggest that reducing BOS as part of treatment may help patients with GHS. Further research is now required to replicate these results in a larger sample and to directly examine shoulder muscle activity to investigate which muscles may influence GHS in response to changing BOS. Future work could also aim to determine whether the reduction in GHS was directly attributable to a reduced BOS or the effort associated with moving from sitting to standing

Clinicopathological significance of EZH2 mRNA expression in patients with hepatocellular carcinoma

Enhancer of zeste homologue 2 (EZH2), a member of the polycomb group protein family, plays a crucial role in the regulation of embryonic development and has been associated with the regulation of the cell cycle. Recently, several studies have shown that EZH2 is highly expressed in aggressive tumours, including human breast cancer, prostate cancer, and lymphomas. We thus analysed EZH2 expression using real-time reverse transcription–polymerase chain reaction, and correlated its expression status with various clinicopathological parameters in 66 patients with hepatocellular carcinoma (HCC). We found high expression of EZH2 in human liver cancer cell lines. Furthermore, EZH2 gene-expression levels in tumour tissue specimens (0.34±0.52) were significantly higher (P<0.0001) than those in the corresponding nontumour tissue specimens (0.07±0.09). The incidence of cancer cell invasion into the portal vein was significantly higher (P<0.001) in the high EZH2 expression group (26 of the 33, 79%) than in the low expression group (13 of the 33, 39%). However, there was no significant difference in the disease-free survival rate between the two groups. The findings of this study indicate that EZH2 mRNA expression was upregulated in human HCC and may play an important role in tumour progression, especially by facilitating portal vein invasion

Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)